/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.dispatcher;

import org.apache.flink.api.common.time.Time;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.runtime.blob.TransientBlobService;
import org.apache.flink.runtime.leaderelection.LeaderElectionService;
import org.apache.flink.runtime.resourcemanager.ResourceManagerGateway;
import org.apache.flink.runtime.rest.handler.RestHandlerConfiguration;
import org.apache.flink.runtime.rest.handler.RestHandlerSpecification;
import org.apache.flink.runtime.rest.handler.job.JobSubmitHandler;
import org.apache.flink.runtime.rest.handler.legacy.ExecutionGraphCache;
import org.apache.flink.runtime.rest.handler.legacy.metrics.MetricFetcher;
import org.apache.flink.runtime.rpc.FatalErrorHandler;
import org.apache.flink.runtime.webmonitor.WebMonitorEndpoint;
import org.apache.flink.runtime.webmonitor.WebMonitorExtension;
import org.apache.flink.runtime.webmonitor.WebMonitorUtils;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;
import org.apache.flink.util.ConfigurationException;
import org.apache.flink.util.ExceptionUtils;
import org.apache.flink.util.FlinkException;

import org.apache.flink.shaded.netty4.io.netty.channel.ChannelInboundHandler;

import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ScheduledExecutorService;

/** REST endpoint for the {@link Dispatcher} component. */
public class DispatcherRestEndpoint extends WebMonitorEndpoint<DispatcherGateway> {

    private WebMonitorExtension webSubmissionExtension;

    public DispatcherRestEndpoint(
            GatewayRetriever<DispatcherGateway> leaderRetriever,
            Configuration clusterConfiguration,
            RestHandlerConfiguration restConfiguration,
            GatewayRetriever<ResourceManagerGateway> resourceManagerRetriever,
            TransientBlobService transientBlobService,
            ScheduledExecutorService executor,
            MetricFetcher metricFetcher,
            LeaderElectionService leaderElectionService,
            ExecutionGraphCache executionGraphCache,
            FatalErrorHandler fatalErrorHandler)
            throws IOException, ConfigurationException {

        super(
                leaderRetriever,
                clusterConfiguration,
                restConfiguration,
                resourceManagerRetriever,
                transientBlobService,
                executor,
                metricFetcher,
                leaderElectionService,
                executionGraphCache,
                fatalErrorHandler);

        webSubmissionExtension = WebMonitorExtension.empty();
    }

    @Override
    protected List<Tuple2<RestHandlerSpecification, ChannelInboundHandler>> initializeHandlers(
            final CompletableFuture<String> localAddressFuture) {
        List<Tuple2<RestHandlerSpecification, ChannelInboundHandler>> handlers =
                super.initializeHandlers(localAddressFuture);

        // Add the Dispatcher specific handlers

        final Time timeout = restConfiguration.getTimeout();

        JobSubmitHandler jobSubmitHandler =
                new JobSubmitHandler(
                        leaderRetriever, timeout, responseHeaders, executor, clusterConfiguration);

        handlers.add(Tuple2.of(jobSubmitHandler.getMessageHeaders(), jobSubmitHandler));

        return handlers;
    }

    @Override
    protected Collection<Tuple2<RestHandlerSpecification, ChannelInboundHandler>>
            initializeWebSubmissionHandlers(CompletableFuture<String> localAddressFuture) {
        if (restConfiguration.isWebSubmitEnabled()) {
            try {
                final Time timeout = restConfiguration.getTimeout();

                webSubmissionExtension =
                        WebMonitorUtils.loadWebSubmissionExtension(
                                leaderRetriever,
                                timeout,
                                responseHeaders,
                                localAddressFuture,
                                uploadDir,
                                executor,
                                clusterConfiguration);

                return webSubmissionExtension.getHandlers();
            } catch (FlinkException e) {
                if (log.isDebugEnabled()) {
                    log.debug("Failed to load web based job submission extension.", e);
                } else {
                    log.info(
                            "Failed to load web based job submission extension. "
                                    + "Probable reason: flink-runtime-web is not in the classpath.");
                }
            }
        } else {
            log.info("Web-based job submission is not enabled.");
        }

        return Collections.emptyList();
    }

    @Override
    protected CompletableFuture<Void> shutDownInternal() {
        final CompletableFuture<Void> shutdownFuture = super.shutDownInternal();

        final CompletableFuture<Void> shutdownResultFuture = new CompletableFuture<>();

        shutdownFuture.whenComplete(
                (Void ignored, Throwable throwable) -> {
                    webSubmissionExtension
                            .closeAsync()
                            .whenComplete(
                                    (Void innerIgnored, Throwable innerThrowable) -> {
                                        if (innerThrowable != null) {
                                            shutdownResultFuture.completeExceptionally(
                                                    ExceptionUtils.firstOrSuppressed(
                                                            innerThrowable, throwable));
                                        } else if (throwable != null) {
                                            shutdownResultFuture.completeExceptionally(throwable);
                                        } else {
                                            shutdownResultFuture.complete(null);
                                        }
                                    });
                });

        return shutdownResultFuture;
    }
}
